xifevent(3) [hpux man page]

XIfEvent()																XIfEvent()

Name
  XIfEvent - wait for event matched in predicate procedure.

Synopsis
  XIfEvent(display, event_return, predicate, args)
	Display *display;
	XEvent *event_return;
	Bool (*predicate)();
	char *args;

Arguments
  display   Specifies a connection to an X server; returned from XOpenDisplay().

  event_return
	    Returns the matched event.

  predicate Specifies the procedure to be called to determine if the next event satisfies your criteria.

  args	    Specifies the user-specified arguments to be passed to the predicate procedure.

Description
  XIfEvent() checks the event queue for events, uses the user-supplied routine to check if one meets certain criteria, and removes the match-
  ing event from the input queue.  XIfEvent() returns only when the specified predicate procedure returns True for an event.   The  specified
  predicate  is  called  once for each event on the queue until a match is made, and each time an event is added to the queue, with the argu-
  ments display, event_return, and arg.

  If no matching events exist on the queue, XIfEvent() flushes the request buffer and waits for an appropriate event to arrive.  Use  XCheck-
  IfEvent() if you don't want to wait for an event.

  For more information, see Volume One, Chapter 8, Events.

See Also
  XQLength(),	XAllowEvents(),   XCheckIfEvent(),   XCheckMaskEvent(),  XCheckTypedEvent(),  XCheckTypedWindowEvent(),  XCheckWindowEvent(),
  XEventsQueued(), XGetInputFocus(), XGetMotionEvents(), XMaskEvent(),	XNextEvent(),  XPeekEvent(),  XPeekIfEvent(),  XPending(),  XPutBack-
  Event(), XSelectInput(), XSendEvent(), XSetInputFocus(), XSynchronize(), XWindowEvent().

Xlib - Input Handling															XIfEvent()

XIfEvent(3X11)															    XIfEvent(3X11)

NAME

       XIfEvent, XCheckIfEvent, XPeekIfEvent - check the event queue with a predicate procedure

SYNOPSIS

       XIfEvent(display, event_return, predicate, arg)
	       Display *display;
	       XEvent *event_return;
	       Bool (*predicate)();
	       XPointer arg;

       Bool XCheckIfEvent(display, event_return, predicate, arg)
	       Display *display;
	       XEvent *event_return;
	       Bool (*predicate)();
	       XPointer arg;

       XPeekIfEvent(display, event_return, predicate, arg)
	       Display *display;
	       XEvent *event_return;
	       Bool (*predicate)();
	       XPointer arg;

ARGUMENTS

       Specifies  the  user-supplied  argument that will be passed to the predicate procedure.	Specifies the connection to the X server.  Returns
       either a copy of or the matched event's associated structure.  Specifies the procedure that is to be called to determine if the next  event
       in the queue matches what you want.

DESCRIPTION

       The  XIfEvent  function	completes  only  when the specified predicate procedure returns True for an event, which indicates an event in the
       queue matches.  XIfEvent flushes the output buffer if it blocks waiting for additional events.  XIfEvent removes the  matching  event  from
       the queue and copies the structure into the client-supplied XEvent structure.

       When  the  predicate  procedure finds a match, XCheckIfEvent copies the matched event into the client-supplied XEvent structure and returns
       True. (This event is removed from the queue.) If the predicate procedure finds no match, XCheckIfEvent returns False, and the output buffer
       will have been flushed. All earlier events stored in the queue are not discarded.

       The  XPeekIfEvent  function  returns  only  when the specified predicate procedure returns True for an event. After the predicate procedure
       finds a match, XPeekIfEvent copies the matched event into the client-supplied XEvent structure without removing the event from  the  queue.
       XPeekIfEvent flushes the output buffer if it blocks waiting for additional events.

SEE ALSO

       XAnyEvent(3X11), XNextEvent(3X11), XPutBackEvent(3X11), XSendEvent(3X11)

       Xlib -- C Language X Interface

																    XIfEvent(3X11)